Stent-graft having supported transition stent and method

ABSTRACT

A stent-graft includes a graft material having a main body, a first leg, a second leg, and a transition region where the first leg and the second leg meet the main body. A main body transition stent is coupled to the main body. A transition stent support including a gusset is coupled to the graft material such that a transition apex of the main body transition stent is interposed between the gusset and the graft material, the transition apex being aligned with the transition region. The transition apex, which is susceptible to failure, is stabilized by the gusset in combination with a supporting ligament. The gusset and supporting ligament prevent flexing of the transition apex and the associated failure thereof.

RELATED APPLICATIONS

This application is a divisional of pending U.S. patent application Ser.No. 15/266,283, entitled “STENT-GRAFT HAVING SUPPORTED TRANSITION STENTAND METHOD”, filed Sep. 15, 2016, which is incorporated herein bereference for all purposes.

BACKGROUND Field

The present application relates to an intra-vascular device and method.More particularly, the present application relates to a device fortreatment of intra-vascular diseases.

Description of Related Art

A conventional bifurcated stent-graft typically includes a radiallyexpandable reinforcement structure, formed from a plurality of annularstent rings, and a cylindrically shaped bifurcated layer of graftmaterial defining lumens to which the stent rings are coupled.Bifurcated stent-grafts are well known for use in human vessels.

To illustrate, endovascular aneurysmal exclusion is a method of using abifurcated stent-graft to exclude pressurized fluid flow from theinterior of an aneurysm, thereby reducing the risk of rupture of theaneurysm and the associated invasive surgical intervention. However, thebifurcated stent-graft is constantly being subjected to external forces,e.g., due to the pressurized fluid flow. This external force can causethe bifurcated stent-graft to fail over time.

SUMMARY

A stent-graft includes a graft material having a main body, a first leg,a second leg, and a transition region where the first leg and the secondleg meet the main body. A main body transition stent is coupled to themain body. A transition stent support including a gusset is coupled tothe graft material such that a transition apex of the main bodytransition stent is interposed between the gusset and the graftmaterial, the transition apex being aligned with the transition region.The transition apex, which is susceptible to failure, is stabilized bythe gusset in combination with a supporting ligament. The gusset andsupporting ligament prevent flexing of the transition apex and theassociated failure thereof.

These and other features in accordance with various embodiments will bemore readily apparent from the detailed description set forth belowtaken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is an anterior perspective view of a bifurcated stent-graft inaccordance with one embodiment.

FIG. 2 is a posterior perspective view of the bifurcated stent-graft ofFIG. 1 in accordance with one embodiment.

FIG. 3 is an enlarged plan view of a region III of the bifurcatedstent-graft of FIG. 1 in accordance with one embodiment.

Common reference numerals are used throughout the drawings and detaileddescription to indicate like elements.

DETAILED DESCRIPTION

FIG. 1 is an anterior perspective view of a bifurcated stent-graft 100,e.g., an aortic bifurcated stent-graft, in accordance with oneembodiment. FIG. 2 is a posterior perspective view of bifurcatedstent-graft 100 of FIG. 1 in accordance with one embodiment. Referringnow to FIGS. 1 and 2 together, bifurcated stent-graft 100 includes amain body 102, a short, e.g., first, leg 104, and a long, e.g., second,leg 106.

Main body 102 extends from a proximal end 108 of bifurcated stent-graft100 to legs 104, 106. Main body 102 defines a main lumen 110. Short leg104 extends from main body 102 to a distal end 112 of short 104. Longleg 106 extends from main body 102 to a distal end 114 of long leg 106.Legs 104, 106 define branch lumens 116, 118, respectively. Main lumen110 is bifurcated into branch lumens 116, 118.

As used herein, the proximal end of a prosthesis such as bifurcatedstent-graft 100 is the end closest to the heart via the path of bloodflow whereas the distal end is the end furthest away from the heartduring deployment. In contrast and of note, the distal end of thecatheter is usually identified to the end that is farthest from theoperator (handle) while the proximal end of the catheter is the endnearest the operator (handle). However, those of skill in the art willunderstand that depending upon the access location, the stent-graft anddelivery system description may be consistent or opposite in actualusage.

Bifurcated stent-graft 100 includes graft material 120 and stents 122,sometimes called stent rings 122, coupled to graft material 120. At mainbody 102, graft material 120 is cylindrical having a substantiallyuniform diameter. Similarly, at short leg 104, graft material 120 iscylindrical. Further, at long leg 106, graft material 120 iscylindrical. However, in other embodiments, graft material 120 varies indiameter at one or more of main body 102, short leg 104, and long leg106.

In one embodiment, graft material 120 is non-permeable, e.g., ispolyester terephthalate (PET), expanded polyester terephthalate (ePET),or other non-permeable graft material. As graft material 120 isnon-permeable, blood or other fluid does not pass through graft material120.

A transition region 124 is defined at the intersection of main body 102,short leg 104, and long leg 106. Transition region 124 is sometimescalled the crotch of bifurcated stent-graft 100.

Stents 122 include main body stents 126, short leg stents 128, and longleg stents 130, sometimes called main body stent rings 126, short legstent rings 128, and long leg stent rings 130, respectively.Illustratively, stents 122 are self-expanding structures, e.g., formedof nickel titanium alloy (nitinol), or other shaped memory material.Stents 122 are attached to graft material 120 with an attachmentstructure, for example, stitching, adhesive, or other attachment meansin various embodiments.

Main body stents 126 are coupled to main body 102. Main body stents 126include a main body transition stent 126A at transition region 124. Moreparticularly, main body transition stent 126A is the most distal of mainbody stents 126 and directly adjacent short leg 104 and long leg 106.

Short leg stents 128 are coupled to short leg 104. Short leg stents 128include a short leg transition stent 128A, sometimes called a first legtransition stent 128A, adjacent main body 102. More particularly, shortleg transition stent 128A is the most proximal of short leg stents 128and directly adjacent main body transition stent 126A.

Long leg stents 130 are coupled to long leg 106. Long leg stents 130include a long leg transition stent 130A, sometimes called a second legtransition stent 130A, adjacent main body 102. More particularly, longleg transition stent 130A is the most proximal of long leg stents 130and directly adjacent main body transition stent 126A.

A length L1 of short leg 104 is less than a length L2 of long leg 106.Although FIG. 1 is referred to as an anterior perspective view and FIG.2 is referred to as a posterior perspective view, the views are notlimiting. For example, FIG. 1 can be a posterior perspective view andFIG. 2 can be an anterior perspective view. Generally, providing shortleg 104 and long leg 106 with different lengths L1, L2 provides a modeof adjustment of bifurcated stent-graft 100 to accommodate variations inanatomy. In another embodiment, short leg 104 and long leg 106 have thesame length. For clarity of description, the view of FIG. 1 and featurestherein shall be referred to as anterior and the view of FIG. 2 andfeatures therein shall be referred to as posterior. However, in light ofthis disclosure, those of skill in the art will understand that theterms “anterior” and “posterior” may be reversed depending upon theparticular deployment of bifurcated stent-graft 100.

Main body transition stent 126A includes an anterior transition apex 132and a posterior transition apex 134 both aligned with transition region124. Anterior transition apex 132 is directly opposite posteriortransition apex 134 on main body 102.

In one embodiment, bifurcated stent-graft 100 is deployed to excludepressurized fluid flow from the interior of an aneurysm, therebyreducing the risk of rupture of the aneurysm and the associated invasivesurgical intervention. However, bifurcated stent-graft 100 is constantlybeing subjected to external forces, e.g., due to the pressurized fluidflow. This external force is concentrated at transition region 124 andat transition apexes 132, 134. More particularly, repeated flexing ofapexes 132, 134 is undesirable and can cause main body transition stent126A to fail (break) at apexes 132, 134. As described below and inaccordance with one embodiment, apexes 132, 134 are supported andprevented from failing.

Paying particular attention now to FIG. 1, main body transition stent126A further includes a first anterior leg apex 136, a second anteriorleg apex 138, a first anterior transition strut 140, and a secondanterior transition strut 142. First anterior leg apex 136 is adjacentshort leg 104 and second anterior leg apex 138 is adjacent long leg 106.First anterior transition strut 140 extends from first anterior leg apex136 to anterior transition apex 132. Second anterior transition strut142 extends from second anterior leg apex 138 to anterior transitionapex 132.

Paying particular attention now to FIG. 2, main body transition stent126A further includes a first posterior leg apex 144, a second posteriorleg apex 146, a first posterior transition strut 148, and a secondposterior transition strut 150. First posterior leg apex 144 is adjacentlong leg 106 and second posterior leg apex 146 is adjacent short leg104. First posterior transition strut 148 extends from first posteriorleg apex 144 to posterior transition apex 134. Second posteriortransition strut 150 extends from second posterior leg apex 146 toposterior transition apex 134.

Referring again to FIGS. 1 and 2 together, bifurcated stent-graft 100further includes a transition stent support 152. Transition stentsupport 152 supports and isolates main body transition stent 126A. Inone embodiment, transition stent support 152 is a graft material, e.g.,similar to graft material 130. Transition stent support 152 is attachedto graft material 130 with an attachment structure, for example,stitching, adhesive, or other attachment means in various embodiments.

Transition stent support 152 includes an anterior, first, gusset 154, aposterior, second, gusset 156, and a transition region support 158.Gussets 154, 156 are sometimes called patches. Transition region support158 extends from anterior gusset 154 over transition region 124 toposterior gusset 156.

Anterior gusset 154 is triangular shaped. Anterior gusset 154 coversanterior transition apex 132, first anterior leg apex 136, secondanterior leg apex 138, first anterior transition strut 140, and secondanterior transition strut 142. More particularly, anterior transitionapex 132, first anterior leg apex 136, second anterior leg apex 138,first anterior transition strut 140, and second anterior transitionstrut 142 and interposed between, sometimes called sandwiched orencapsulated by, anterior gusset 154 and graft material 120.

Anterior gusset 154 stabilizes and support anterior transition apex 132,first anterior leg apex 136, second anterior leg apex 138, firstanterior transition strut 140, and second anterior transition strut 142.In this manner, anterior gusset 154 prevents repeated flexing ofanterior transition apex 132 and failure thereof.

A third anterior transition strut 160 extends from first anterior legapex 136 and a fourth anterior transition strut 162 extends from secondanterior leg apex 138. Third anterior transition strut 160 and fourthanterior transition strut 162 are uncovered by and exposed from anteriorgusset 154.

Similarly, posterior gusset 156 stabilizes and support posteriortransition apex 134, first posterior leg apex 144, second posterior legapex 146, first posterior transition strut 148, and second posteriortransition strut 150. In this manner, posterior gusset 156 preventsrepeated flexing of posterior transition apex 134 and failure thereof.

A third posterior transition strut 164 extends from first posterior legapex 144 and a fourth posterior transition strut 166 extends from secondposterior leg apex 146. Third posterior transition strut 164 and fourthposterior transition strut 166 are uncovered by and exposed fromposterior gusset 156.

FIG. 3 is an enlarged plan view of a region III of bifurcatedstent-graft 100 of FIG. 1 in accordance with one embodiment. In FIG. 3,anterior gusset 154 is indicated in a dashed line to allow visualizationof features covered by anterior gusset 154.

Referring now to FIG. 3, bifurcated stent-graft 100 further includes ananterior supporting ligament 302. Anterior supporting ligament 302 is alinear element, e.g., a thread, rod, or other supporting member.

Anterior supporting ligament 302 is connected to and extends betweenfirst anterior leg apex 136 and second anterior leg apex 138. Statedanother way, first and second anterior leg apexes 136, 138 adjacent toanterior transition apex 132 are connected together with anteriorsupporting ligament 302. Anterior supporting ligament 302 prevents firstanterior leg apex 136 from moving away from second anterior leg apex138, i.e., maintains a fixed distance D1 between first anterior leg apex136 and second anterior leg apex 138. By preventing relative motionbetween first anterior leg apex 136 and second anterior leg apex 138,anterior supporting ligament 302 prevents flexing of anterior transitionapex 132 and the associated failure thereof.

In one embodiment, anterior supporting ligament 302 is attached to graftmaterial 120 and/or anterior gusset 154 by an anterior attachmentstructure 304, e.g., stitching. This stabilizes anterior supportingligament 302 thus enhancing the stabilization of first anterior leg apex136 relative to second anterior leg apex 138. In one embodiment, ananterior attachment structure 306, e.g., stitching, attaches anteriorgusset 154 to graft material 120 and extends around first anteriortransition strut 140, anterior transition apex 132, and second anteriortransition strut 142. Anterior attachment structure 304 and anteriorattachment structure 306 can be separate stitching or regions of acommon stitch.

Although FIG. 3 is described in relation to the region III of FIG. 1,the discussion is equally applicable to the region III of FIG. 2. Moreparticularly, the discussion is relation to the region III of FIG. 1 ofanterior supporting ligament 302, first anterior leg apex 136, secondanterior leg apex 138, anterior transition apex 132, anterior attachmentstructure 304, and anterior attachment structure 306 is equallyapplicable to the region III of FIG. 2 including a posterior supportingligament, first posterior leg apex 144, second posterior leg apex 146,posterior transition apex 134, a posterior attachment structure, and aposterior attachment structure, respectively.

This disclosure provides exemplary embodiments. The scope is not limitedby these exemplary embodiments. Numerous variations, whether explicitlyprovided for by the specification or implied by the specification ornot, such as variations in structure, dimension, type of material andmanufacturing process may be implemented by one of skill in the art inview of this disclosure.

What is claimed is:
 1. A method comprising: coupling a main bodytransition stent to a main body of a graft material adjacent to a firstleg and a second leg of the graft material; and interposing a transitionapex of the main body transition stent between a transition stentsupport and the graft material, the transition apex being aligned with atransition region of the graft material where the first leg and thesecond leg meet the main body.
 2. The method of claim 1 furthercomprising coupling apexes of the main body transition stent adjacent tothe transition apex together with a supporting ligament.
 3. The methodof claim 2 wherein the transition stent support and the supportingligament support the transition apex.